[Billyboy]

First, let me say that sounds like a brilliant dare. As a big self-spanking fan, I will definitely try this, although I'm not such a big fan of spanking with the bare hand. (I can take a lot on my bare bottom, but hate hurting my hand )

Let's see if I've got this right:
1. First spank, let's say I give myself 100 spanks. Earns 100 points
2. Masturbation period 100 points = 100 seconds to jack off. After 100 seconds, I lose half the points, which leaves me with 50.
3. Spanking time - 30 seconds for as many spanks as I can do, let's say I do 60, so now I have 110 points.
4. Masturbation period, I have 110 points, so 110 seconds to jack off. At the end, I lose half, 55 points remain.
5. Spanking - 30 seconds. I do 30 spanks so 55+30=85 points
6. Masturbation period 85 seconds, drops to 43 points

And this continues until....

Question:
You said, 'You must have 20 or less points before you are allowed to cum.' 20 points when? At the beginning of a masturbation period? At the end of a masturbation period after the points are halved?